This invention relates to an inspection template for semiconductor die or packages. The image of the semiconductor device can be compared with the template to verify size, orientation, correct placement on an underlying pad, and other characteristics.
A frequent step during the manufacture of semiconductor devices such as integrated circuits is the visual inspection of the die and package. Due to the small sizes of the devices, inspection is commonly performed at an optical inspection station providing magnification, lighting, measuring rulers and instruments, and other capabilities. For example, such a station could be based on a Bausch and Lomb microscope with stereo viewing capatility, zoom magnification capability, and interchangeable lens and lighting sources. Where direct measurement with rulers or micrometers is unwieldy, it is known to use a glass reticle installed in the lens turret or eye piece tube of the microscope. The reticle provides a pattern of intersecting fine lines, or a measurement scale superimposed on the magnified image. In this way, dimensions can be observed and compared to engineering drawings or process specifications.
Reticles are commonly made from glass with the lines or scale markings deposited by chrome or aluminum coating and etching. Reticles with standard patterns and measuring scales are commonly available. Reticles with custom patterns can be obtained at much greater expense. But since a semiconductor manufacturing facility will typically be manufacturing dozens of different die and package combinations, having a custom reticle for each combination is unlikely. A reticle is commonly installed by screwing apart the optical tube of the microscope, placing the reticle within the tube and holding it in position by screwing a field adapter into the tube to hold the reticle against the eyepiece lens.
This method of semiconductor device inspection has several disadvantages. The lack of specialized reticle patterns allows errors to occur in reading and interpreting readings from the scales. In addition, a second step is then required to compare the reading to a drawing or specification. The method of installing and removing the reticles, is quite time consuming and can lead to excess wear on the threads of the microscope tube.
The glass reticles known in the art also have several disadvantages. The metal coating and etching processes used to pattern the reticles are costly. It requires specialized equipment and substantial time to produce the reticles. Being made of glass, the reticles are quite fragile, and likely to shatter if dropped onto a table top or to the floor.